1. Field of the Invention
The present invention relates to a therapeutic training device for posteriorly repositioning the lower jaw of an edentulous or toothless patient to its optimal position. The invention also relates to a system for fitting an edentulous patient with dentures using such a device.
2. Description of the Related Prior Art
Individuals who wear dentures for an extended period of time experience a drifting forward of their mandible as can be seen by the protruded position of the mandible in the facial profile illustrated in FIG. 6 as compared to the profile shown in FIG. 7. This condition impairs the function of artificial teeth since such teeth are manufactured for a particular patient's bite at the time before the mandible has drifted forward. The drifting forward of the mandible also detracts from the individual's appearance.
Devices are known which can be used to treat conditions of the temporomandibular joint (TMJ), i.e., the joint between the temporal bone or the compound bone on the side of the skull of humans and the mandible.
U.S. Pat. No. 4,671,766 to Norton discloses an intraoral, orthotic device for stabilizing the muscles used for mastication. The device includes two halves, one for the maxillary arch and one for the mandibular arch. Both halves have projecting wings that interact when the mouth is closed to exercise the jaw muscles.
U.S. Pat. No. 4,810,192 to Williams discloses a device used for healing the TMJ after it has been subjected to trauma. A first stage of the device acts as a mandibular orthodontic repositioning appliance, and a second stage is a mouth guard providing maxillary and mandibular teeth seats. The two stages interact together when positioned in the mouth to protect the upper and lower teeth and hold the TMJ in its functional position.
It is also known in the art to employ bite plates fitted into the mouth of a patient to record the patient's bite. The patient makes an uninterrupted, oscillatory motion of a lower bite plate relative to an upper bite plate, and in doing so traces a so-called "Gothic Arch" on a contact plate mounted onto one of the bite plates. Similar devices are used to correlate or equilibrate dentures in the mouth of the patient so that they will be balanced for proper contact and comfort to the wearer.
U.S. Pat. No. 3,068,570 to Thompson et al., for example, discloses a dental device including a lower and upper dental plate. Mounted to the lower dental plate is a base member having a striking pin attached thereto. Mounted on the upper dental plate is a contacting plate. The striking pin is used to trace a Gothic Arch on the contact plate.
Thompson et al. teaches that its invention is particularly useful when used in conjunction with certain artificial teeth disclosed in U.S. Pat. No. 2,617,192 to Goddard. Another patent relating to these types of artificial teeth is U.S. Pat. No. 3,252,220 also to Goddard. The Goddard '220 patent teaches dentures including teeth having a masticating surface which is concave and which includes a ridge on one edge which contacts the masticating surface of a corresponding tooth. For reasons which will become clear later, this type of artificial teeth is preferred for use in connection with the present invention.
The device disclosed in Thompson et al. has never before been used to treat the TMJ. The invention utilizes such a device (modified with certain additional features which will be discussed below) as a training device in combination with artificial teeth of the type disclosed in Goddard '220 to reposition the mandible posteriorly and maintain the repositioned mandible in its optimal position for its function and aesthetics. The training device is used by a patient over a period of several weeks to exercise the muscles of the face and jaws and urge the mandible to go back to its original, optimal position. After this has occurred, the optimal centric position is captured in plaster and casts mounted, as is conventional, to fit an individual with dentures. The dentures utilize teeth of the type disclosed in Goddard '220 and become, in effect, a therapeutic device that continues to accommodate any further posterior repositioning the mandible may make.
When the dentures are made in this way, i.e., when an edentulous individual's mandible is correctly positioned prior to being fitted with dentures, a patient experiences significantly less movement of the denture bases on the gum tissue and hence much less soreness and discomfort.